1. Field of the Invention
The present invention relates to a display, and more particularly to a display that is capable of multi-touch sensing, and a driving method thereof.
2. Description of the Related Art
Generally, a touch panel is a type of user interface that may be attached to a surface of a display device, where an electrical characteristic is changed at a touch area where a finger of the user or other instrument contacts the touch panel so as to sense the touch area thereof. The application for touch panels extend to small portable terminals, office equipment and the like. If two or more touches are simultaneously generated, the touch panel might malfunction or any one of the touches may be selected by a pre-set program.
FIGS. 1-3 show known multi-touch devices that have attempted to overcome the limitations of multi-touch recognition systems. Referring to FIG. 1, the multi-touch device of the related art includes a transparent acrylic plate 11 and first through fourth IR (infrared) arrays 12A-12D. IR arrays 12A-12D include infrared light emitting diodes (IRLED), and IR photo detectors (IRPD). FIG. 2 shows that a hand of the user or a pen is directly in contact with the transparent acrylic plate 11.
The first through fourth IR arrays 12A-12D are arranged to face a side surface of the transparent acrylic plate 11. Infrared light is radiated from the IRLEDs 13 through the transparent acrylic plate 11. The infrared light is received by the corresponding IRPDs 14. In this state, if a finger of the user or a pen is in contact with the transparent acrylic plate 11, the infrared light is scattered and is not received at the corresponding IRPD 14. Accordingly, the multi-touch device in FIG. 1 may recognize an erroneous touch location.
A multi-touch device of the related art in FIG. 1 includes the IR arrays 12A-12D arranged at a side surface of the transparent acrylic plate 11, and is advantageous because it is thin. However, the multi-touch device of the related art is disadvantageous because the multi-touch recognition capability is inaccurate due to a direct illumination by infrared light. Further, the effective display surface is reduced by an area occupied by the IR arrays 12A-12D. FIG. 2 and FIG. 3 show a projector-type multi-touch device. The multi-touch device includes a camera and projector module 30, which are located a rear portion of the transparent acrylic plate 11.
If a hand of the user is in contact with an arbitrary point on the transparent acrylic plate 11, an infrared ray is scattered by the hand. The scattered infrared ray is incident on the camera and projector module 30. Such a scattered infrared ray SIR is sensed by the camera and projector module 30. Because the distance between the transparent acrylic plate 11 and the camera and projector module 30 is relatively long, the multi-touch device in FIG. 2 and FIG. 3 occupies a wide space. Furthermore, since the multi-touch device in FIG. 2 and FIG. 3 displays an image using a projector, the type of display device and the design of the display device is limited. Additionally, the life span of a the projection lens is limited.
Furthermore, the multi-touch devices in FIG. 2 and FIG. 3 transmit signals from the camera and projector module 30 to an external computer via a cable, and process the signals by the external computer. Thus, the system is complicated, the space occupied by the components is large, and a signal transmitting path is long.